Loop-taker and bobbin-case device for sewing machines



2 Sheets-Sheet l Gizafles AKQSSZQF c. A. KESSLER Filed Oct 19, 1935 LOOP TAKER AND BOBBIN CASE DEVICE FOR SEWING MACHINES June 29, 1937.

June 29, 1937. c A, KE 2,085,699

LOOP TAKER AND BOBBIN CASE DEVICE FOR SEWING MACHINES Filed Oct. 19, 1935 2 Sheets-She et 2 FT %harles A. KSSZ8P Patented June 29, 1937 UNITED STATES PATENT OFFICE LOOP-TAKER. AND BOBBIN-CASE DEVICE FOR SEWING MACHINES Application October 19, 1935, Serial No. 45,717

10 Claims. (Cl. 112-181) This invention relates to circularly moving loop-taker and bobbin-case devices for lockstitch sewing machines and more particularly to loop-takers such as the rotary hooks disclosed in U. S. Patents No. 1,125,669; dated Jan. 19,

1915; and No. 1,995,278; dated Mar. 19, 1935.

A loop-taker of the type in question is provided with a circular raceway in which is journaled a peripheral bearing rib of a substantially cylindrical bobbin-case which carries the lower threadmass. It is the function of the loop-taker to seize a loop of thread from the sewing machine needle, draw out or expand such loop and cast it about the bobbin-case, after which the needle- 16 thread take-'up device of the machine comes into action to draw the needle-loop up tothe work and complete the stitch.

To restrain the bobbin-case against rotation with the loop-taker, it is customary to provide 20 the bobbin-case with a rotation-restraining notch which is loosely entered by a rotation-restraining tongue mounted on the machine frame. In operation, the frictional drag of the rotary looptaker upon the bobbin-case tends to hold one side-wall or shoulder of the rotation-restraining notch against the rotation-restraining tongue. Each needle-loop cast about the bobbin-case must therefore pass between these contacting walls of the rotation-restraining tongue and the complemental rotation-restraining 'notch in the thread-case, before such loop is free to be drawn up to the work.

In sewing machines which do not employ mechanical devices for opening the needle-loop escape-gap between the bobbin-iase and itsrotation-restraining means, the opening bf such gap is commonly effected by a wedging action of the thread-loop which, in being drawn up by the take-up, opens and squeezes itself through the 40 gap by reacting against the adjacent wall of the rotation-restraining tongue; the thread-loop being pinched in so doing. This action, however, is not conducive to the production of satisfactory stitching at high speeds with threads of various twists and qualities and in work of various textures and thicknesses. Some threads tend to twist on themselves or kink and this tendency' is difficult to deal with in taking up the needleloops after they have been passed around the bobbin-case. Pinching of the thread-loops seems to be particularly provocative of kinking or knotting.

' Mechanical bobbin-case openers, such as disclosed in U. S. patents to Ringe; No. 1,404,146; of Jan. 17, 1922; and Plumley; No. 1,612,647; of

Dec. 28, 1926; have been proposed, but such openers entail the expense of additional mechanism and they limit the speed at which the machine maybe satisfactorily operated. Moreover, they are noisy in operation and cause excessive wear 5 and tear of the hook and bobbin-case elements. Hence, the elimination of mechanical bobbin-case openers is highly desirable of accomplishment.

The device of my U. S. Patent No. 1,995,278, cited, deals mainly with the problem of drawing 10 out the needle-loop and casting it. about the bobbin-case, while the present improvement deals chiefly with the control and handling of the needleloop after it has been cast about the bobbincase and is being drawn up; it being at this stage 15 of the stitch-forming cycle that the escape of such loop from the bobbin-case rotation-restraining means usually takes place.

The present improvement aims to provide a loop-taker and bobbin-case device having quiet running, Wear resisting and stitching characteristics which render it superior to any such device heretofore produced. 7

A further object of the invention isto provide for the opening of the needle-loop escape-gap between the bobbin-case andits rotation-restrainer, without the provision of special mechanical escape-gap-opening means and without subjecting the needle-loop to a squeezing or pinching action.

According to the present improvement, the loop-taker and bobbin-case device has been modified so as to function to maintain control of the needle-loop as the latter is being drawn up by the take-up, thus avoiding twisting or kinking 35 of the needle-loop and to retain control of the needle-loop long enough and so lead the thread thereof and coordinate the action of the under' thread mechanism and the sewing machine takeup, that the loop-tightening action of the take- 40 up will cause the needle-thread loop to exert a backward tangential pull on the bobbin-case in a direction to open the needle-loop escape-gap between the bobbin-case and the usual stationary rotation-restraining tongue; the needle-loop es- 45 caping freely from the opened gap without being squeezed or pinched by the walls of such gap.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from which the several features of the invention and the advantages at- 55 tained thereby will be readily understood by those skilled in the art.

In the accompanying drawings Fig. 1 is a front end elevation'of a sewing machine embodying the invention. Fig. 2 is a top plan view of the loop-taker and bobbin-case device of the machine. Fig. 3 is a vertical axial section through the loop-taker and bobbin-case device. Fig. 4 is a front face view of the peripherally ribbed bobbin-case carrier element. Fig. 5 is a rear face view of the same. Fig. 6 is a perspective view of the bobbin-case rotation-restraining bar. Fig. 7 is a perspective view of the loop-taker as showing the needle-loop under control as it is being drawn up by the take-up. Fig. 8 is a similar view showing the needle-loop being tightened to exert a tangential pull on the thread-case to open the needle-loop escape-gap between the thread-case and Fig. 8 is a plan view of the parts of Fig. 8. Fig. 9 is a similar view showing the escape-gap open and the needle-loop escaping therefrom. Fig. 9 is a plan view of the parts of Fig. 9. Fig. 10 is a section on the line ll0, Fig. 9*. Fig. 11 is a view, similar to Figs. '7, 8 and 9, but at a slightly later stage of the cycle, showingthe needleloop after it has escaped from the gap between the bobbin-case and its rotation-restraining bar. Figs. 12 and 13 are perspective views of the looptaker or rotary hook element. Fig. 14 is a perspective view of the removable thread-case element. Fig. 15 is a perspective view of the bobbin which fits in the removable thread-case element, and Fig. 16 is a perspective view of the face of the removable bobbin-case element.

The invention will be described as embodied in a sewing machine having a bed I and bracketarm head 2 carrying the usual needle-bar 3 and presser-bar 4. The needle-bar carries the usual eye-pointed needle and the presser-bar carries the usual presser-foot 6'. The needle-bar 3 is reciprocated by the usual link-connection I with the-crank 8 carried by the mainshaft 9 which also actuates the well known link or crankoperated take-up In; the latter being preferably constructed substantially in accordance with the disclosure of U. S. Patent No. 462,398; dated Nov. 3, 1891. The work is fed under the presser-foot 6 by means of the usual four-motion feed-dog ll.

Cooperating with the needle is the under thread mechanism or loop-taker and bobbin-case device ,a, Fig. 1, with which the present invention is particularly concerned. The loop-taker is preferably a cup-shaped body l2, Figs. 12 and 13, having a loop-seizing beak l2, a loop-controlling tail l3 and a circular raceway l4 in which is journaled the peripheral bearing rib l5 of the stationary bobbin-case carrier-element l6. The hook-body i2 is carried as usual by the hookshaft 12" which preferably makes two complete rotations to one rotation of the main shaft 9. The peripheral bearing rib l5 of the bobbin-case carrier-element has a gap in its upper portion to provide the loop-detaining shoulder l1 and a radialloop-confining shoulder I8, the latter being preferably advanced or disposed somewhat beyond the vertical axial plane bb of the threadcase carrier, as shown in Fig. 2. By positioning the loop-confining shoulder l8 closer to the loopdetaining shoulder H, the angle :c. Fig. 10, of the gap between the shoulders I! and I8 has been reduced in the present instance to approximately 43. The gap 1 Fig. 10, in the hook raceway I4 is also small, being in the present instance apits rotation-restraining ban.

proximately 60. Thus, the total maximum gap in the bearing surfaces between the bobbin-case and the hook-body has, contrary to the usual practice, been materially reduced and in the present instance amounts to approximately 103, giving a bearing surface of 360-103 or approximately 257. This aids materially in eliminating clatter and reducing wear of the bobbin-case in the hook-raceway as the hook-raceway gap passes the gap in the bobbin-case bearing rib. The advance and radial disposition of the loop- 7 confining shoulder l8 also delay the release of the contracting needle-loop from the latter and are advantageous in attaining the objects of the invention, as will be understood as the description proceeds.

The bobbin-case carrier-element I6 is formed at its needle-loop cast-off side with a needle-loopcontrolling flange l9 in the upper portion of the front face of which is formed the rotationrestraining notch 20 loosely entered by the tongue 2| of the rotation-restraining bar 22 mounted on the under side of the bed I. The tail l3 of the rotary hook member l2 has a needle-loop-supporting surface l3 which is disposed at a distance from the axis of the hookmember greater than the maximum radial dimension of the peripheral bearing rib [5 of the bobbin-case and overhangs such bearing rib. This surface holds the needle-loop off of the bearing rib I5 and cooperates with the flange l9 to control the needle-loop. The edge of the flange I9 is cut away or notched at 23 at the needle-loop cast-off side of the rotation-restraining notch 20 to momentarily receive a portion of the contracting needle-loop after the latter has been safely lifted onto the tail J3 by the flange l9, as will be further explained.

Removably fitted to the bobbin-case carrierelement 16 is the companion bobbin-case element 24 which carries the bobbin 25 of under thread. The bobbin-case element 24 preferably has a threading slot 26 cut inwardly from the rim thereof at a steep angle to the point 21 from which the slot 28 leads substantially peripherally of the bobbin-case element 25 to the threaddelivery aperture 29 under the usual bobbinthread tension-spring 30. The rim of the bobbin-case element 24 is also preferably cut away slightly at 3|. It is understood that the complete bobbin-case includes the two separable elements I6 and 24.

The operation is as follows:

The loop-taker beak l2 seizes a loop of thread from the needle 5. expands such loop and casts it about the bobbin-case in the usual manner, as shown in Fig. 1; the work-limb of the needle-loop passing in frontof or across the exposed face of the bobbin-case and the take-up limb behind the bobbin-case. As soon as the loop-taker reaches cast-off position, the crankoperated take-up l0 begins its quick up-stroke and draws the needle-loop off of the point l2 of the hook and onto the loop-controlling tail l3, as shown in Fig. 7. The purpose of the flange I9 is to lift the cast needle-loop high enough so that it will be drawn with certainty over the point of the tail I3 which prevents the loop from rubbing on the bearing rib l5 and being damaged, frayed or soiled thereby.

As the action continues from the position shown in Fig. 7, the slight amount of slack in the loop is removed by the take-up and the loop is drawn by the take-up into the notch 23, as shown in- Fig. 8; the needle-loop escape-gap 32 between the in Fig. 11. tail I3 and is drawn up to the work by the takerotation-restraining shoulder 33 of the notch 20 and the rotation-restraining tongue 2| being in closed condition at this time due to the drag of the rotary hook-body l2 on the bobbin-case carrier-element l6. Thus, in the position shown in Figs. 8 and 8, all slack has been removed from the needle-loop and the thread of the needleloop between the rotation-restraining notch 20, Fig. 8, and the notch 23 in the flange [9 leads substantially tangentially of the bobbin-case away from the rotation-restraining shoulder 33. The take-up in its further action exerts a tension on the thread which is transmitted to the needle-loop and causes the latter in its contrac tion to exert a tangential backward pull on the bobbin-case at the shoulders I 8 and 33, in the direction of the dotted arrows, Fig. 8 This backward tangential pull on the bobbin-case by the needle-loop, opens the needle-loop escape-gap 32, as shown in Figs. 9 and 9 through which the thread-loop readily passes without being pinched or squeezed between the opposed walls of the needle-loop escape-gap 32. Upon referring to Fig. 10, it will be understood that by disposing the loop-confining shoulder I8 substantially radially of the bobbin-case, instead of rounding it off as shown in Fig. 6 of U. S. Patent No. 1,995,278, referred to, the needle-loop may be caused to exert .the desired backward pull against the shoulder I 8 without wedging itself between the bearing rib I and the hook-raceway [4. It will be further understood that the advance of the loop-confining shoulder 18 in a direction toward the loop-arresting shoulder I1 delays the release of the contracting needle-loop from interlocking relation with the rotary-hook and bobbin-case elements and insures that the contracting needleloop will invariably be drawn by the take-up onto the loop-controlling tail I3 from which it cannot escape until after the loop has been drawn through the escape gap 32. Shortly after the needle-loop escapes from the gap 32, the end l4, Figs. and 12, of the hook-raceway I 4 passes the loop-confining shoulder l8 and releases the needle-loop which is around the tail l3 as shown Finally, the loop is dropped by the up to complete the stitch.

Numerous exacting tests of sewing machines embodying the present improvement have demonstrated their ability to sew with uniformly set stitches and without breaking thread at speeds up to 4,500 stitches per minute in work of varying thicknesses and with thread of various qualities without adjustment of the tension device.

So far as I am aware, I am the first to provide a lock-stitch sewing machine having a circularly moving loop-taker and a stationary bobbin-case journaled therein, in which machine the needleloop escape-gap between the stationary bobbincase and its cooperating rotation-restraining element is opened by a pull exerted on the bobbincase in. a direction to open such gap, by the needle-loop which has been cast about the bobbincase by the loop-taker and is being contracted by the take-up; the action being distinguished from the heretofore common wedging action of the needle-loop in opening the escape-gap by reaction against a wall of the usual rotationrestraining tongue.

It will be obvious to those skilled in the art that the invention may, without departure from its essential attributes; be embodied in various specific forms other than that shown and described,

which latter is to be considered in all respects as restraining illustrative and not restrictive; reference being had to the appended claims rather than to the foregoing description to indicate the scope of the invention.

Having thus set forth the nature of the invention, what I claim herein is:

1. The combination with a reciprocatory nee dle, of a rotary hook having a loop-seizing beak, a loop-controlling tail and a circular raceway, a

. bobbin-case having a peripheral bearing-rib journaled in said raceway and a rotation-restraining shoulder, a rotation-restraining element engaged by said shoulder, and means to remove all slack from and exert a strain on the cast-needle loop on said tail'prior to escape of said loop from interlocking relation with said rotary hook and bobbin-case to cause said loop to exert a tangential pull on the bobbin-case in a direction contrary to the direction of rotation of said hook and open a needle-loop escape-gap between the rotation-restraining shoulder and the rotationelement without subjecting the thread to a pinching action therebetween.

2. In a sewing machine, the combination with an eye-pointed reciprocatory needle, of a rotary hook having a loop-seizing beak, a loop-controlling tail and a raceway, a stationary bobbin-case having a peripheral bearing rib journaled in said raceway and a rotation-restraining notch, arotation-restraining tongue loosely entering said notch, and means to remove all slack from and exert a strain on the needle-loop which has been cast about the bobbin-case before the loop is released from interlocking relation with the hookbody and bobbin-case, thereby causing said loop to exert a backward tangential pull on said bobbin-case and open the needle-loop escape-gap between the rotation-restraining tongue and a wall of said rotation-restraining notch without subjecting the thread to a pinching action.

3. In a sewing machine, the combination with an eye-pointed needle and a crank-operated takeup, of a rotary hook having a loop-seizing beak,- a loop-controlling tail and a raceway, a stationary bobbin-case having a peripheral bearing rib journaled in said raceway and a rotation-restraining notch, the tail of said hook having a needle-loop-supporting surface disposed at a distance from the axis of said hook greater than the maximum radial dimension of and overhanging said peripheral bearing rib, said bobbin-case having a face flange to lift the contracting needleloop onto said tail, and said flange having a needle-loop-receiving notch therein adjacent said rotation-restraining notch, into which needleloop-receiving notch the needle-loop is tightened by the take-up while said loop is on said tail and caused to exert a backward tangential pull on the bobbin-case to. open the needle-loop escape-gap between the rotation-restraining tongue and the rotation-restraining notch without subjecting the thread to a pinching action.

4. The combination with a reciprocatory needle, of a rotary hook having a loop-seizing beak and a circular raceway, a bobbin-case having a peripheral bearing rib journaled in said raceway, said rib having a gap therein providing a loopdetaining shoulder and a loop-confining shoulder, the latter being disposed beyond the vertical axial plane of the rotary hook, said bobbin-case also relation with said rotary hook and bobbin-case, thereby causing the needle-loop to exert a backward pull on said loop-confining shoulder and open the needle-loop escape-gap between said rotation-restraining tongue and a Wall of said rotation-restraining notch.

5. The combination with a reciprocatory needle, a rotary hook; a. thread-case journaled therein and having a rotation-restraining notch, and a stationary rotation-restraining element loosely entering said notch, of means to control the limbs of the cast needle-loop and remove all slack from and tighten such loop at a time such that a portion or portions of such loop extending peripherally of the bobbin-case will exert a backward tangential pull on the bobbin-case and open the needle-loop escape-gap between said rotation-restraining tongue and a wall of said notch, without subjecting the thread to a pinching action.

6. In a sewing machine, a rotary hook having a loop-seizing beak, a loop-controlling tail and a raceway, a bobbin-case having a peripheral bearing-rib journaled in said raceway and formed with a gap providing loop-detaining and loopconfining shoulders, said bobbin-case also having at its loop cast-off side a face flange which is formed in its upper end face portion with a rotation-restraining notch, the outer edge of said flange being cut away at the needle-loop-discharge side of said notch to momentarily receive a portion of the contracting needle-loop after the latter has been safely lifted onto said tail by said flange.

7. A bobbin-case carrier element for rotary hook sewing machines comprising a cup-shaped member having a peripheral bearing-rib and a needle-loop controlling flange which is formed with a rotation-restraining shoulder and the loopcontrolling edge of which flange is cut away adjacent said shoulder.

8. Under thread mechanism for lock-stitch sewing machines comprising a cup-shaped rotary hook body formed with a loop-seizing beak, a loop-controlling tail, and a raceway having a gap therein between said beak and tail of approximately 60, a bobbin-case element having a peripheral bearing-rib journaled in said raceway and having a gap therein of approximately 43,

said bobbin-case also having a needle-loop-controlling flange which is formed with a rotationrestraining shoulder and the loop-controlling edge of which flange has a radius of curvature greater than that of said peripheral bearing-rib and is cut away adjacent said shoulder.

9. The combination with a reciprocatory needle, of a rotary loop-taker having a, loop-seizing beak and a circular raceway with a gap therein, a bobbin-case having a peripheral bearing rib journaled in said raceway and a rotation-restraining shoulder, said bearing rib having a, gap therein to provide a needle-loop-detaining shoulder and a needle-loop-confining shoulder, a stationary rotation-restraining element in contact with which the rotation-restraining shoulder of said bobbin-case is held by the frictional drag of said loop-taker, and means to remove all slack from and exert a strain on the cast needle-loop at a time prior to release of the needle-loop from interlocking relation with the loop-taker and bobbin-case, thereby causing the strained needleloop to exert a backward tangential pull on the bobbin-case and open a needle-loop escape-gap between the contacting walls of said rotationrestraining shoulder and rotation-restraining element without reacting against said element and being pinched thereby.

10. The combination with a reciprocatory needle, of a rotary hook having a loop-seizing beak, a loop-controlling tail and a circular raceway, a bobbin-case having a. peripheral bearing rib journaled in said raceway, said rib having a gap therein providing a loop-detaining shoulder and a substantially radial loop-confining shoulder, said bobbin-case also having a rotation-restraining shoulder, a rotation-restraining element against which said rotation-restraining shoulder is held by the frictional drag of said hook upon said bobbin-case, and means to tighten the cast needle-loop on said tail prior to escape of said needle-loop from the loop-confining shoulder of said bearing rib, thereby causing said needle-loop to exert a backward pull on said loop-confining shoulder and open a needle-loop escape-gap between said rotation-restraining element and said rotation-restraining shoulder.

CHARLES A. KESSLER. 

